leaded to unleaded conversion

[Sam2]

G'day,

Just wondering if anyone has converted an engine from leaded to unleaded?

As I understand it, the valve stems and valve seats need to be replaced. To replace the valve seats the engine needs to be heated to 100 degrees ?

Is it a job an enthusiastic backyarder can do, or better left to a professional?

Cheers,

Sam.

[Evan Bottcher]

My understanding is that pretty much all modern (Giulietta and Giulia twin-cam onwards I'm thinking) Alfa engines have hardened valve seats as a matter of course - that because they have alloy heads that they have pressed in valve seats, and that Alfa valve seats hardened and therefore strong enough to survive unleaded fuel.  I think the only issue might be pinging (pre-ignition) if you run on low octane regular unleaded (91 octane), consider running 98 octane unleaded (ultimate or optimax).

I'm vastly unqualified though - please someone correct me 

Fwiw - I'm running our Alfasud with a 33 1.5 motor on BP Ultimate fuel with no apparent side effects.

[a sharp]

Evan is right you will have no problems with valves from using unleaded in any of the alloy headed engines, but stay away from the low octane standard type unleaded fuels to stop pinning. Remember your car was designed for 98 octane leaded super, Optimax and most of the other top of the line 98 octane unleaded fuels will be fine, you might find you can get away with 95 octane but I havn't tried it so can't offer a opinion.

[Sam]

Hi folks,

In the past, I've been told that  Alfettas  (which included Guliettas) can't run unleaded fuel.

Here, I've heard the opposite.

I have a Vin Sharp modified head on my 1979 Alfetta sedan.
A while ago I called Vin to help settle it once and for all, and he said it can't run unleaded fuel.

Now I'm hearing the opposite.

I'm a little confused. !

Sam

[vin sharp]

Hi folks,

In the past, I've been told that  Alfettas  (which included Guliettas) can't run unleaded fuel.

Here, I've heard the opposite.

I have a Vin Sharp modified head on my 1979 Alfetta sedan.
A while ago I called Vin to help settle it once and for all, and he said it can't run unleaded fuel.

Now I'm hearing the opposite.
Sam.

Hi Sam,
I don't specifically recall any particular conversation, but unless you asked about running low octane ULP or you have an unusually high compression ratio, you should be able to run quite OK on 98 ULP.
Most of the 70's 105s and Alfettas have reasonable material in their valves and seats. It's not as good as later TwinSpark 75s and V6s, but remember that in the US they have been running ULP since the early 70's, and from what I've seen of US imported Spiders, the seats are the same as ours. Of course, if I'm replacing seats in a head, harder material is used, and eventually most will end up with these, but I don't see any need for wholesale panic about it.
Valve seat wear and recession is always going to happen as a normal part of use, but there is no reason why reasonable service can't be achieved. Of course an additive like flashlube or similar can help the situation and is recommended. We run 2 road Alfettas as daily drivers quite happily on 98 ULP.
My main concern is that people use Premium or High Octane , I would always prefer 98 as a minimum, and have their ignition advance tuned to it. Detonation (pinging)from low quality fuel or over-advanced ignition timing (worn distributor internals) is probably responsible for far more dramas than any other causes. Head gasket compression leaks, broken rings, cracked bores are high on the list of detonation woes. 
Vin.